package com.hadoop.training.examples;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.*;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.util.*;

import org.apache.hadoop.io.LongWritable;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.*;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.input.TextInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
import org.apache.hadoop.mapreduce.lib.output.TextOutputFormat;


public class WordCount extends Configured implements Tool {

	public static class WordCountMap extends Mapper<LongWritable, Text, Text, IntWritable>
	{
		private final static IntWritable one = new IntWritable(1);
		private Text word = new Text();
		
		@Override
		public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException
		{
			String line = value.toString();
			StringTokenizer tokenizer = new StringTokenizer(line);
			while(tokenizer.hasMoreTokens())
			{
				word.set(tokenizer.nextToken());
				context.write(word, one);
			}
		}
	}
	
	public static class WordCountReducer extends Reducer<Text, IntWritable, Text, IntWritable>
	{
		public void reduce(Text key, Iterable<IntWritable> values, Context context) throws IOException, InterruptedException
		{
			int sum = 0;
			for(IntWritable value: values)
			{
				sum += value.get();
			}
			context.write(key, new IntWritable(sum));
		}
		
	}
	
	public int run(String[] args) throws Exception  {
		// TODO Auto-generated method stub
		Job job = new Job(getConf());
		job.setJarByClass(WordCount.class);
		job.setJobName("wordcount");
		
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);
		
		job.setMapperClass(WordCountMap.class);
		job.setCombinerClass(WordCountReducer.class);
		job.setReducerClass(WordCountReducer.class);
		
		
		job.setInputFormatClass(TextInputFormat.class);
		job.setOutputFormatClass(TextOutputFormat.class);
		
		
		FileInputFormat.setInputPaths(job, new Path(args[0]));
		FileOutputFormat.setOutputPath(job, new Path(args[1]));
		
		boolean success = job.waitForCompletion(true);
		return success ? 0: 1;
	}
	
	/**
	 * @param args
	 * @throws Exception 
	 */
	public static void main(String[] args) throws Exception {
		// TODO Auto-generated method stub
		int result = ToolRunner.run(new WordCount(), args);
		System.exit(result);
	}


	

	
}
